Minimally invasive surgery (MIS) has allowed physicians to carry out many surgical procedures with less pain and disability than conventional, open surgery. However, unlike conventional open surgery, where the surgical site is readily accessible through a large incision, MIS typically requires the surgeon to operate remotely by inserting and manipulating instruments through small punctures, openings, or access sites in the body wall. A hollow cannula may be placed in the puncture to create a minimally invasive entry point. Cannulas, typically have tubular passages with a diameter ranging in size from 5 to 20 millimeters (mm) and are often sealed to maintain positive pressure within the peritoneal cavity to facilitate pneumoperitoneum during laparoscopic surgery. One or more cannulas may be inserted into the body for any given operation. Medical instruments, such as grippers, manipulators, cutters, suturing (sewing) devices, etc., are then inserted through the one or more cannulas.
When considering what size cannula to use for a given procedure, surgeons often face a tradeoff. On the one hand, smaller cannulas can lead to better patient outcomes including less peri-operative pain, rapid return of normal functions, earlier return to home and work, and reduced herniation risk. On the other hand, smaller cannulas can reduce the selection of MIS instruments available to the surgeon. For example, while many MIS instruments may have a shaft diameter that will fit through a smaller cannula, such instruments are often limited only to having straight shafts. By contrast, larger cannulas also accommodate surgical instruments having bent shafts that require a larger diameter cannula tube for passage.
Surgical instruments having a bend are often more ergonomic, enabling a surgeon to work more comfortably, efficiently, and to reach areas inside the patient which would otherwise be very difficult to access with a straight-shafted MIS instrument. In light of these advantages, this can lead surgeons to use larger size cannulas to ensure a successful, efficient procedure at the possible expense of patient recovery time for the reasons discuss above.
In response to this situation, surgical instruments with articulation control have been developed. With these instruments, the surgeon is able to adjust a dial, knob, lever, or other control on the proximal end of the instrument to first straighten the shaft. In its straight profile, the shaft can easily be passed through a smaller diameter cannula tube. Once the distal end of the MIS instrument is inside the patient, the surgeon can then readjust the control on the proximal end to articulate the tip of the device into an operating position. When the instrument needs to be removed, the surgeon can further adjust the control on the proximal end to articulate the distal shaft of the device into a straight position so that it can be removed through the cannula. Unfortunately, while such controlled-articulation devices do allow surgeons to use smaller cannulas, they can complicate the surgical procedure by requiring two hands to operate the device, one to hold the proximal end of the device and another to adjust the articulation control. The surgeon may not have a free hand for the articulation control, since he or she may also be manipulating another device through a separate cannula at the same time with his or her other hand. As a result, a surgical assistant may be needed to help out in these situations, or the surgeon may temporarily have to let go of the other device, possibly leaving it momentarily unattended.
Therefore, there is a need for technology which 1) will enable a surgeon to use ergonomically bent or angled MIS instruments 2) in conjunction with smaller cannula sizes to improve patient outcomes and recovery times 3) while freeing the surgeon from the need to control articulation of the MIS instrument.